The present invention relates generally to a cartooning and animating process used to create visual media, and more particularly to digital implementations of this process to render line art versions, and optionally also into colored line art and line art image sequences. Historically the term xe2x80x9crotoscopingxe2x80x9d has been used to describe manual variations of this process, and the inventors adopt that term herein as well for their automated digital process.
Rotoscoping has been in wide use since its invention in 1914 by Max and Dave Fleischer. These brothers coined the term xe2x80x9crotoscopexe2x80x9d to describe a machine which they constructed to assist in manually tracing live action movies, exposure by exposure, to create cartoons and animations. Today the term rotoscoping is widely used to describe the process of projecting film images one frame at a time onto a surface, where line art representations of actors or objects are then traced, or xe2x80x9cinked,xe2x80x9d by hand. Optionally, these outlines may be filled with color, or xe2x80x9cpainted.xe2x80x9d See, Shamus Culhane, ANIMATION FROM SCRIPT TO SCREEN, St. Martin""s Press, New York, 1988, at pp. 33 and 327; and Christopher Finch, SPECIAL EFFECTS: CREATING MOVIE MAGIC, Abbeville Press, New York, 1984, at pp. 35 and 247.
Many well known examples of rotoscoping exist, although it is not commonly appreciated that rotoscoping was a key technology in their creation. For example, Walt Disney Studios used rotoscoping to a limited extent in its animated production of xe2x80x9cSnow Whitexe2x80x9d in the 1930""s, and then subsequent to that started to heavily rely upon it for its animated productions.
Rotoscoping is not, however, limited to merely the genre of cartoon-like amusements. Recent examples can also be found in the Horror and Science Fiction genres, which have their own particular needs for realistic appearing special effects. For example, it was used as a hand retouching tool when creating the film xe2x80x9cPoltergeist,xe2x80x9d to enhance a scene where a house imploded into a small hole. Similarly, the film xe2x80x9c2001: A Space Odysseyxe2x80x9d used rotoscoping to wed small models of space craft with hand-drawn outer space background scenes. Extensive use of rotoscoping was made in the film xe2x80x9cStar Wars,xe2x80x9d to add elements such as the light sabers wielded in fight scenes by the Luke Skywalker and Darth Vader characters, and to enhance explosions.
Unfortunately, a common thread applicable to all rotoscoping to date, and particularly so to rotoscope cartoon or animation production, is its labor intensive nature. Since animation projects of any appreciable size require artist-months or even artist-years of effort, the size of the labor force needed for such rotoscoping projects can result in very high expense. Further, the nature of the labor involved often makes particular demands upon the artist-employees. Artists are generally known for their tendency to be temperamental and transient employees. Hand rotoscope inking and painting is xe2x80x9cproduction linexe2x80x9d type work, which many artists regard as demeaning in view of their particular skills and training. Therefore, somewhat understandably, many artists approach rotoscope work as merely an entry level or temporary position, while they maneuver for promotion or look for more glamorous work elsewhere. This often adds considerably to xe2x80x9cnon-wagexe2x80x9d personnel costs of rotoscoping projects, and introduces work consistency and quality problems which project management must allocate additional resources to control.
In sum, what is needed today is an improved rotoscoping process, one which advances this valuable art from a prohibitively expensive and tediously labor intensive one which has been stagnant since the 1930""s.
Accordingly, it is an object of the present invention to provide an automated process for carrying out image to line art rendering.
Another object of the invention is to provide a computer assisted process for carrying out specific image area to specialized line art rendering, to carry subtle and particularly expressive detail through the rendering process.
And, another object of the invention is to provide a computer assisted process for coloring of line art renderings.
Briefly, a first preferred embodiment of the present invention is an image rendering process, comprising obtaining an original image and digitally rendering it into a rotoscoped line art representation of the original image.
Considerable optional variation is possible in the stage of obtaining the original image. Some representative examples include using a color-key background, to perform matte operations, to optimize the execution speed of the process, or to optimize the quality of the product of the process. Advantageous use of increased contrast, distinctive color, increased lighting intensity, sharper focus, and reduced motion blur are representative examples of set-up operations which may optionally be used while obtaining the original image. The image may initially be obtained in a non-digital format, such as photography, and scanned into a digital format; or the image may be directly obtained in a digital format.
Considerable optional variation is also possible in the stage of rendering the original image into a rotoscoped line art representation. A representative example of this includes scaling the image up in size and converting it into monochrome, then applying a sequence of levels filtering, high-pass filtration, contrast enhancement, darkening, reduction to final size, lining subject borders for consistency, and removing visual xe2x80x9cnoisexe2x80x9d from what is now the rotoscoped line art representation.
Briefly, a second preferred embodiment of the present invention is an improved image rendering process, comprising taking an original image and an already rotoscoped line art image and producing an enhanced line art representation. A monochrome version of the image termed a xe2x80x9cfacexe2x80x9d image is created from the rotoscoped image, and a generally conventional alpha channel is produced from the original image. Unwanted content is then removed from the rotoscoped image, and an artist reviews and cleans up the result. One or more key regions are then selected in the face image, their contrast is enhanced, and the face image is integrated back into the rotoscoped image, subject to designation in the alpha channel of what is desired content in the ultimate version of rotoscoped image produced by this particular process. A subsequent or concurrent coloring process may optionally be applied to the rotoscoped image which is produced.
An advantage of the present invention is that it provides an automated process for converting individual images and image sequences into line art renderings. This essentially constitutes automating the monochrome portions of the manual process known as rotoscoping. Using the invention, individual images (e.g., photographs, or digital xe2x80x9cscreen capturesxe2x80x9d) can be rendered into line art cells. Image sequences can similarly be rendered into line art animations, with no inherent limitation upon the length or order of the sub-sequences used. For example, in this manner entire animated movies may be created. Another example is the creation of computer products such as games and training materials, where sub-sequences are indexably addressed for interactive access by users.
Another advantage of the invention is that it optionally includes a computer assisted sub-process for specially rendering specific image areas into line art. This can be used to carry subtle detail through the rendering process, and even enhance such detail. Generally, basic rotoscoping has not been able to handle particularly expressive portions of some images, such as human faces, hand expressions, and intricately detailed objects. This optional capability may be used on individual images and entire image sequences as well, thereby providing entirely new capabilities in the art of animation.
Another advantage of the invention is that it optionally includes a computer assisted sub-process for coloring line art renderings.
Another advantage of the invention is that it considerably reduces the manual efforts required to produce rotoscopings, as well as enhanced and colorized rotoscopings. As little as one relatively artistically unskilled person may now produce entire feature film length animations or computer CD ROM interactive products with the inventive process, whereas in the past teams of hundreds of skilled artists and coordinating managers would have previously been required. Now an individual or a small team can bring major projects to complete and polished fruition, yet fully meet quality expectations of the commercial marketplace.
Another advantage of the invention is that it is considerably cheaper to use than manual rotoscope inking techniques to produce line art renderings, and painting techniques to produce colorizations. Obvious economy is derived by reduction in labor force size. Indirect further economy is also obtained from elimination of infrastructure to support a sizable labor force. Office space and peripheral staff, such as payroll clerks, are two ready examples. Work materials such as paper, ink, paint, photographic film stock, electricity for projection equipment, etc. are replaced with computer resources which are, in overall balance, cheaper and better tolerated environmentally.
And, another advantage of the invention is that it is considerably faster to use than manual rotoscoping inking techniques to produce line art renderings, and painting techniques to produce colorizations. In addition to the obvious benefits of speeding up project completion times, this provides quality benefits. Overall project quality can be improved because testing may be very quickly performed using the present invention. Further, since it can be expensive or even impossible to recapture images when initial images are found totally defective, prompt image quality testing can provide great economic benefit. This is particularly important when color-key techniques are used when capturing images, since these techniques require particularly high quality initial images. Using the present invention, sample images can quickly be put through the entire rendering process, to catch even the most subtle of flaws very soon after images are captured. Particularly prompt test results are possible when digital type image capture techniques are used. However, even photographic images may be tested by putting them through the now much faster rendering process. Prompt development of the actual image film stock may be carried out, or parallel still frame images may be captured, developed, and rendered to insure that the actual motion picture film reel image sequences will be of suitable quality.
These and other objects and advantages of the present invention will become clear to those skilled in the art in view of the description of the best presently known mode of carrying out the invention and the industrial applicability of the preferred embodiment as described herein and as illustrated in the several figures of the drawings.